MDEV-20077 Warning on full history partition is delayed until next DML statement

Moved LIMIT warning from vers_set_hist_part() to new call
vers_check_limit() at table unlock phase. At that point
read_partitions bitmap is already pruned by DML code (see
prune_partitions(), find_used_partitions()) so we have to set
corresponding bits for working history partition.

Also we don't do my_error(ME_WARNING|ME_ERROR_LOG), because at that
point it doesn't update warnings number, so command reports 0 warnings
(but warning list is still updated). Instead we do
push_warning_printf() and sql_print_warning() separately.

Under LOCK TABLES external_lock(F_UNLCK) is not executed. There is
start_stmt(), but no corresponding "stop_stmt()". So for that mode we
call vers_check_limit() directly from close_thread_tables().

Test result has been changed according to new LIMIT and warning
printing algorithm. For convenience all LIMIT warnings are marked with
"You see warning above ^".

TODO MDEV-20345 fixed. Now vers_history_generating() contains
fine-grained list of DML-commands that can generate history (and TODO
mechanism worked well).

1 files changed, 43 insertions, 10 deletions

diff --git a/sql/partition_info.cc b/sql/partition_info.cc
index f523415f6cc..90ef388f3b9 100644
--- a/sql/partition_info.cc
+++ b/sql/partition_info.cc
@@ -835,6 +835,9 @@ bool partition_info::has_unique_name(partition_element *element)
 
 int partition_info::vers_set_hist_part(THD *thd)
 {
+  if (!vers_require_hist_part(thd))
+    return 0;
+
   if (table->pos_in_table_list &&
       table->pos_in_table_list->partition_names)
   {
@@ -856,12 +859,8 @@ int partition_info::vers_set_hist_part(THD *thd)
       vers_info->hist_part= next;
       records= next_records;
     }
-    if (records > vers_info->limit)
-    {
-      if (next == vers_info->now_part)
-        goto warn;
+    if (records >= vers_info->limit && next != vers_info->now_part)
       vers_info->hist_part= next;
-    }
     return 0;
   }
 
@@ -883,11 +882,45 @@ int partition_info::vers_set_hist_part(THD *thd)
     }
   }
   return 0;
-warn:
-  my_error(WARN_VERS_PART_FULL, MYF(ME_WARNING|ME_ERROR_LOG),
-           table->s->db.str, table->s->table_name.str,
-           vers_info->hist_part->partition_name);
-  return 0;
+}
+
+
+/**
+  Warn at the end of DML command if the last history partition is out of LIMIT.
+*/
+void partition_info::vers_check_limit(THD *thd)
+{
+  if (!vers_info->limit ||
+      vers_info->hist_part->id + 1 < vers_info->now_part->id)
+    return;
+
+  /*
+    NOTE: at this point read_partitions bitmap is already pruned by DML code,
+    we have to set read bits for working history partition. We could use
+    bitmap_set_all(), but this is not optimal since there can be quite a number
+    of partitions.
+  */
+  const uint32 sub_factor= num_subparts ? num_subparts : 1;
+  uint32 part_id= vers_info->hist_part->id * sub_factor;
+  const uint32 part_id_end= part_id + sub_factor;
+  DBUG_ASSERT(part_id_end <= num_parts * sub_factor);
+  for (; part_id < part_id_end; ++part_id)
+    bitmap_set_bit(&read_partitions, part_id);
+
+  ha_partition *hp= (ha_partition*)(table->file);
+  ha_rows hist_rows= hp->part_records(vers_info->hist_part);
+  if (hist_rows >= vers_info->limit)
+  {
+    push_warning_printf(thd, Sql_condition::WARN_LEVEL_WARN,
+                        WARN_VERS_PART_FULL,
+                        ER_THD(thd, WARN_VERS_PART_FULL),
+                        table->s->db.str, table->s->table_name.str,
+                        vers_info->hist_part->partition_name);
+
+    sql_print_warning(ER_THD(thd, WARN_VERS_PART_FULL),
+                      table->s->db.str, table->s->table_name.str,
+                      vers_info->hist_part->partition_name);
+  }
 }